text: /*
   * ACPI I2C enumeration support
   *
   * Copyright (C) 2012, Intel Corporation
   * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  
  #include <linux/acpi.h>
  #include <linux/device.h>
  #include <linux/export.h>
  #include <linux/i2c.h>
  #include <linux/ioport.h>
  
  ACPI_MODULE_NAME("i2c");
  
  static int acpi_i2c_add_resource(struct acpi_resource *ares, void *data)
  {
  	struct i2c_board_info *info = data;
  
  	if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS) {
  		struct acpi_resource_i2c_serialbus *sb;
  
  		sb = &ares->data.i2c_serial_bus;
  		if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_I2C) {
  			info->addr = sb->slave_address;
  			if (sb->access_mode == ACPI_I2C_10BIT_MODE)
  				info->flags |= I2C_CLIENT_TEN;
  		}
  	} else if (info->irq < 0) {
  		struct resource r;
  
  		if (acpi_dev_resource_interrupt(ares, 0, &r))
  			info->irq = r.start;
  	}
  
  	/* Tell the ACPI core to skip this resource */
  	return 1;
  }
  
  static acpi_status acpi_i2c_add_device(acpi_handle handle, u32 level,
  				       void *data, void **return_value)
  {
  	struct i2c_adapter *adapter = data;
  	struct list_head resource_list;
  	struct i2c_board_info info;
  	struct acpi_device *adev;
  	int ret;
  
  	if (acpi_bus_get_device(handle, &adev))
  		return AE_OK;
  	if (acpi_bus_get_status(adev) || !adev->status.present)
  		return AE_OK;
  
  	memset(&info, 0, sizeof(info));
  	info.acpi_node.handle = handle;
  	info.irq = -1;
  
  	INIT_LIST_HEAD(&resource_list);
  	ret = acpi_dev_get_resources(adev, &resource_list,
  				     acpi_i2c_add_resource, &info);
  	acpi_dev_free_resource_list(&resource_list);
  
  	if (ret < 0 || !info.addr)
  		return AE_OK;
  
  	strlcpy(info.type, dev_name(&adev->dev), sizeof(info.type));
  	if (!i2c_new_device(adapter, &info)) {
  		dev_err(&adapter->dev,
  			"failed to add I2C device %s from ACPI\n",
  			dev_name(&adev->dev));
  	}
  
  	return AE_OK;
  }
  
  /**
   * acpi_i2c_register_devices - enumerate I2C slave devices behind adapter
   * @adapter: pointer to adapter
   *
   * Enumerate all I2C slave devices behind this adapter by walking the ACPI
   * namespace. When a device is found it will be added to the Linux device
   * model and bound to the corresponding ACPI handle.
   */
  void acpi_i2c_register_devices(struct i2c_adapter *adapter)
  {
  	acpi_handle handle;
  	acpi_status status;
  
  	handle = ACPI_HANDLE(adapter->dev.parent);
  	if (!handle)
  		return;
  
  	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
  				     acpi_i2c_add_device, NULL,
  				     adapter, NULL);
  	if (ACPI_FAILURE(status))
  		dev_warn(&adapter->dev, "failed to enumerate I2C slaves\n");
  }
  EXPORT_SYMBOL_GPL(acpi_i2c_register_devices);
  